“Homeland Security” refers to the goal of detecting and defending against threats to public safety posed by potential attack by hostile individuals or groups. Homeland Security applications for radar surveillance differ fundamentally from most military applications. The high price of military radars is justified by the critical and urgent need for protection in combat zones or near high-value assets. The price is affordable because the deployments are confined in time and/or space. Homeland Security, in contrast, deals with threats, such as terrorist attacks, that materialize infrequently and can occur anywhere. Surveillance to counter such threats must be deployed simultaneously across huge areas on a permanent 24/7 basis. Therefore, in the market for sensors used for Homeland Security surveillance, low-cost is not just a competitive advantage, it is a fundamental requirement.
Homeland Security includes such applications as border patrol, law enforcement, critical infrastructure protection (both corporate and public facilities), transportation security, port security and coastal surveillance. All of these applications require cost-effective detection and tracking of small, fast, maneuvering, elusive targets. Targets of interest include (but are not limited to) small watercraft in littoral regions, and snowmobiles on snow or ice cover, or other vehicles. At the present time, low-cost radar systems suitable for these homeland security applications are not operational.
Altogether different problems that also require cost-effective detection and tracking of small, fast, maneuvering, elusive targets are the bird air strike hazard (BASH) problem and the natural resource management (NRM) problem concerning birds. Billions of dollars in damage to aircraft and significant loss of life have been recorded due to birds flying into aircraft, particularly during take-off and landing in the vicinity of airports. At the present time, low-cost radar systems suitable for these avian radar applications are under development.
Practical solutions for the aforementioned applications must be able to provide continuous, day or night, all weather, wide-area situational awareness with automated detection, localization and warnings of threats. The wide-area situational awareness points towards a network of radars operating together to provide a composite picture. The automated warning of threats points toward high-quality target track data with sophisticated criteria to determine suspicious or potentially dangerous target behavior, as well as communication of alerts to users who require that information. Furthermore, practical solutions must also minimize operator interaction due to the fact that system cost includes the cost of human labor needed to operate the system.
Some of the key requirements of the cited applications include:                Low-cost, high-performance radar antennas and transceivers that can be mounted on land-based towers as well as on mobile vehicles and vessels.        Radar processing that can reliably detect and track small, low-RCS, maneuvering targets in dense target and clutter environments.        Automatic threat detection and alert capability to remote users        The formation of radar networks to provide wide-area coverage        Low cost of operation        Low life cycle costs        Data and analysis support for research and development        
While X-band or S-band coherent radar technology used in air traffic control and military radars could be integrated, reconfigured and optimized to satisfy performance requirements for the aforementioned applications, such systems would not be affordable. Typically, each radar sensor would cost in the millions of dollars, not taking into account the life cycle costs of maintaining and operating such systems. The purpose of the invention disclosed herein is to provide a low-cost radar surveillance solution to these problems, where the radar sensor would cost as little as $50,000 or less.
Commercial, off-the-shelf (COTS) marine radars (from companies such as Furuno, Raymarine, Decca, etc.) are very inexpensive due to the fact that they are noncoherent and that millions of them are sold world-wide for use on commercial and recreational vessels. A radar antenna and transceiver can be purchased for under $10,000, depending on the transmitter power and antenna selected. These marine radars exhibit surprisingly good hardware specifications such as transmitter power, receiver characteristics and antenna pattern. However, in operation, these radars deliver mediocre performance for our targets of interest because of their primitive signal processing. They are primarily used for detecting large vessels and shorelines for navigation and collision avoidance purposes.
Combining a COTS marine radar with a digitizer board and a software radar processor that runs on a COTS personal computer (PC) can allow a marine radar to be adapted for other applications. One vendor [Rutter Technologies, www.ruttertech.com] has developed a radar processor for such a system [the Sigma S6 Processor] where the radar processor is tuned for detecting slow-moving floating ice targets (such as ice bergs or bergy bits) in the sea by using scan-to-scan integration techniques over time frames of 20 seconds to 160 seconds (to improve signal to clutter ratio (SCR)) combined with an alpha-beta tracker designed for non-maneuvering targets. This system has been designed for maritime operation on-board a vessel or moored platform and hence does not deal with the formation of radar networks, does not solve the small-RCS, fast, maneuvering target problem, and does not provide low-cost of operation since an operator is needed for each system. In addition, alerts are not automatically provided to remote users for unattended operation.